Raman Spectroscopy Measurements Research Articles

The enhancement of electrical properties of TiO2/xCoFe2O4 nanocomposites for extended applications

The pure TiO2 and TiO2/xCoFe2O4 nanocomposites (0, 2, 4, and 6 wt. %) were synthesized using the sonomechanical method at room temperature. The prepared specimens were studied by scanning electron microscopy (SEM), energy-dispersive X-ray techniques (EDX), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and ac conductivity measurements. The sample exhibited homogeneous and well-distributed spherical nanoparticles of visible surface edges with average grain size ranging from 100 to 200 nm, as shown in the SEM micrograph. Raman spectra analysis showed the characteristic band for TiO2 at 141.2, 233.08, 447.13, 609.55, and 639.4 cm−1. The FTIR confirmed the interaction of CoFe2O4 and TiO2 reflecting the successful formation of nanocomposites. Compared to pristine TiO2, both the dielectric constant (ε') and conductivity were boosted by the inclusion of CoFe2O4. The behavior of the exponent factor (S) with temperature demonstrates that the conduction mechanism is the correlated barrier hopping (CBH) mechanism. The investigation of complex electric modulus established that the vertiginous nanocomposite had a non-Debye-type relaxation. The observed properties prove that TiO2/ xCoFe2O4 (x = 0, 2, 4, and 6 wt. %) nanocomposites are very functional for electric storage applications.

Inert structural transition in 4H and 6H SiC at high pressure and temperature: a Raman spectroscopy study

We conducted Raman spectroscopy measurements of 4H-SiC and 6H-SiC up to 69 GPa and 1023 K to assess the stability and bonding of SiC at high pressure and temperature. Both optic and acoustic modes were observed at wide pressure and temperature ranges. The temperature shifts of the Raman frequencies were fitted by the equation with the Bose–Einstein distribution function, and we found that the shifts were almost insensitive to the pressure. The mode Grüneisen coefficients weakly depend on the pressure and temperature, suggesting the sluggish transition of the crystal structure, unlike the previous experiments showing the transition or decomposition of SiC at high pressure and temperature conditions. Inert transitions are confirmed by Raman measurements and annealing experiments using multiple high-pressure apparatuses. The crystallinity may be a hidden critical parameter in the experiments to determine the stable polytypes of SiC under high pressure and temperature.

Time‐resolved Raman spectroscopy study of rapid compressed silicon and its potential as a Raman pressure scale in a dynamic diamond anvil cell

AbstractThe nature of the nonequilibrium states of materials upon rapid compression/decompression processes in the intermediate regime, between static and shock compression, is an emerging field of high pressure research. Rapid compression experiments were performed to examine the structural response of silicon (Si) up to 11 GPa and over compression rates ranging from 0.011 to 0.325 GPa/s, using a piezo‐driven dynamic diamond anvil cell (dDAC) coupled with time‐resolved Raman spectroscopy. The observed structural stability and the remarkable consistency in the pressure‐dependent Raman shift of the diamond cubic Si (Si‐I) showed its high potential as a Raman pressure scale for compression rate below 0.325 GPa/s. The validity of the derived Si scale was verified by in situ continuously monitoring pressure of two rapid compressed samples, that is, gypsum and ZnO. Results indicated that pressures determined using Si were in good agreement with those estimated from the ruby scale. Success in pressure calibration with Si, during time‐resolved Raman spectroscopy measurements of material under rapid compression using a dDAC, will greatly simplify the required hardware system in home‐laboratory and may also help in reaching a higher signal‐to‐noise in Raman measurement on a short time scale.

The Polychromatic Inscriptions on the Relief Sculpture Deposition from the Cross by Benedetto Antelami in Parma Cathedral, Italy

This paper reports on the studies carried out on engraved inscriptions of the Deposition from the Cross by Benedetto Antelami (1150–1230), a relief sculpture conserved in the Cathedral of Parma (Italy). The inscriptions between the characters show residues of colored material in alternating red- and dark-colored stripes. The purpose of this specific investigation was to identify the materials (pigments and organic binders) used for the polychromy that are still present on the relief sculpture. Seven microsamples were taken to carry out laboratory analyses. In red-colored letters, mercury, and sulfur, constituents of the cinnabar (or vermilion) pigment were easily identified by SEM-EDS. This result is confirmed by Raman spectroscopy and XRD measurements. In the dark letters, carbon, iron, and lead are observed. The presence of materials containing metals is compatible with a mastic encrustation technique. FT-IR, Raman, and XRD techniques clearly detect beeswax, which was probably used as a polishing material. Amino acids and lipids that are typical of eggs have been identified by means of GC-MS investigations, suggesting their use as organic components of the mastic encrustation.

Crystal structure of 4,4′-(disulfanediyl)dipyridinium chloride triiodide

4,4′-(Disulfanediyl)dipyridinium chloride triiodide, C10H10N2S2 2+·Cl−·I3 −, (1) was synthesized by reaction of 4,4′-dipyridyldisulfide with ICl in a 1:1 molar ratio in dichloromethane solution. The structural characterization of 1 by SC-XRD analysis was supported by elemental analysis, FT–IR, and FT–Raman spectroscopic measurements.

TiO2 multi-leg nanotubes for surface-enhanced Raman scattering

Abstract In the recent past, significant research efforts have been put forth to fabricate cost-effective substrates for surface-enhanced Raman scattering (SERS) applications. Here we propose semiconducting TiO2 multi-leg nanotubes and Au nanoparticle-coated TiO2 multi-leg nanotubes (TiO2 MLNTs and Au/TiO2 MLNTs) as SERS substrates. The unique multi-leg architecture of TiO2 nanotubes demonstrated enhanced light-harvesting properties facilitated by an induced photonic absorption edge. Remarkable high SERS sensitivity is observed towards the detection of Methylene blue (MB), up to nM concentration (E.F. ∼104) using TiO2 MLNTs. The same is attributed to the resonantly matched photonic absorption edge of TiO2 MLNTs with the wavelength of incident laser probe light. On the other hand, the Au nanoparticle coating further leveraged the light absorption ability of TiO2 MLNTs with the aid of localized surface plasmon resonance mode. As such, Au/TiO2 MLNTs showed excellent enhancement in SERS sensitivity (E.F. ∼105 , for nM of MB) facilitated by the synergy between the plasmonic modes of Au and the photonic absorption mode of TiO2 MLNTs. UV-Vis diffuse reflectance and Raman spectroscopy measurements are highlighted to elucidate the light absorption and SERS sensitivity of the TiO2 and Au/TiO2 MLNTs.

Study on heat-treated pyrolytic carbon deposited from methane on directly heated carbon fibres

The study investigated the morphology, microstructure, structure, texture, and mechanical properties of heat-treated at 1600 °C and 2000 °C pyrolytic carbon (PyC) deposited from methane using various methods such as scanning electron microscopy (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), Raman spectroscopy, and ultrasonic dynamic measurements of Young's modulus. The PyC was synthesised at 1100 °C using a chemical vapour deposition (CVD) method with direct electrical heating of the two types of carbon fibres (CFs). The results showed that the PyC had a low- and medium-texture (LT and MT PyC). Analysis of the graphitization trajectory allowed the determination of structural changes in the material as a function of temperature, including the growth of crystallites and an increase in the crystallinity proportion without the significant rearrangement within PyC. The crystallite size and the number of interstitial defects has increased with temperature that controlled mechanical properties. Therefore, based on the results obtained, the most suitable composites for further research in the context of electrodes for stimulation of nervous tissue were obtained at the temperature of their synthesis, i.e. at 1100 °C.

Intraoperative spectroscopic evaluation of sentinel lymph nodes in breast cancer surgery

Background and objectivesSentinel lymph node (SLN) biopsy is a standard procedure for patients with breast cancer and normal axilla on imaging. Positive SLNs on histological examination can lead to a subsequent surgery for axillary lymph node clearance (ALNC). Here we report a non-destructive technique based on autofluorescence (AF) imaging and Raman spectroscopy for intra-operative assessment of SLNs excised in breast cancer surgery.MethodsA microscope integrating AF imaging and Raman spectroscopy modules was built to allow scanning of lymph node biopsy samples. During AF-Raman measurements, AF imaging determined optimal sampling locations for Raman spectroscopy measurements. After optimisation of the AF image analysis and training of classification models based on data from 85 samples, the AF-Raman technique was tested on an independent set of 81 lymph nodes comprising 58 fixed and 23 fresh specimens. The sensitivity and specificity of AF-Raman were calculated using post-operative histology as a standard of reference.ResultsThe independent test set contained 66 negative lymph nodes and 15 positive lymph nodes according to the reference standard, collected from 78 patients. For this set of specimens, the area under the receiver operating characteristic (ROC) curve for the AF-Raman technique was 0.93 [0.83–0.98]. AF-Raman was then operated in a regime that maximised detection specificity, producing a 94% detection accuracy: 80% sensitivity and 97% specificity. The main confounders for SLN metastasis were areas rich in histiocytes clusters, for which only few Raman spectra had been included in the training dataset.DiscussionThis preliminary study indicates that with further development and extension of the training dataset by inclusion of additional Raman spectra of histiocytes clusters and capsule, the AF-Raman may become a promising technique for intra-operative assessment of SLNs. Intra-operative detection of positive biopsies could avoid second surgery for axillary clearance.

Promoting Electrochemical CO2 Reduction to Formate via Sulfur‐Assisted Electrolysis

AbstractElectrochemical CO2 reduction reaction (CO2RR) provides a renewable approach to transform CO2 to produce chemicals and fuels. Unfortunately, it faces the challenges of sluggish CO2 activation and slow water dissociation. This study reports the modification of Bi‐based electrocatalyst by S, which leads to a remarkable enhancement in activity and selectivity during electrochemical CO2 reduction to formate. Based on comprehensive in situ examinations and kinetic evaluations, it is observed that the presence of S species over Bi catalyst can significantly enhance its interaction with K+(H2O)n, facilitating fast dissociation of water molecules to generate protons. Further in situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) and in situ Raman spectroscopy measurements reveal that S modification is able to decrease the oxidation state of Bi active site, which can effectively enhance CO2 activation and facilitate HCOO* intermediate formation while suppressing competing hydrogen evolution reaction. Consequently, the S‐modified Bi catalyst achieves impressive electrochemical CO2RR performance, reaching a formate Faradaic efficiency (FEformate) of 91.2% at a formate partial current density of ≈135 mA cm−2 and a potential of −0.8 V versus RHE in an alkaline electrolyte.

Competitive nature of weak anti-localization and weak localization effect in Cr-doped sputtered topological insulator Bi2Se3 thin film

In the present study, we have investigated the effect of magnetic Cr doping on the transport properties of a sputtered Bi2Se3 thin film on the SrTiO3 (110) substrate. The high-resolution x-ray diffraction and Raman spectroscopy measurements revealed the growth of rhombohedral Bi2Se3 thin films. Further electronic and compositional analysis was done by x-ray photoemission spectroscopy and Rutherford backscattering spectroscopy, and the x-value was estimated to be 0.18 in the Bi2−xCrxSe3 thin film. The variation in the resistivity with temperature (2–300 K) revealed the metallic nature in undoped Bi2Se3 up to 30 K and upturn resistivity below 30 K. The Cr-doped Bi2Se3 resistivity data show a traditional semiconducting nature up to 25 K and take an abrupt upturn resistivity below 25 K. The resistivity behavior of both samples was explained by adopting a model that consists of the total resistance, a combination of bulk and surface resistance in parallel. The bulk bandgap value determined by this method is obtained to be 256 meV in an undoped Bi2Se3 thin film. Magnetoconductance data of the undoped thin film revealed a weak anti-localization (WAL) effect, while the Cr-doped thin film showed a weak localization (WL) effect at low temperatures (<50 K). At low magnetic field and low temperature, a competing nature of WAL and WL effects was prominent in the Cr-doped film. A drastic increase in the electrical resistance suggests that Cr doping can significantly modify the electrical properties of Bi2Se3 thin films, which could have potential applications in futuristic devices.

Investigation of overall water splitting process on the 1 T/2H-MxCS catalyst via in situ Raman and IR spectroscopy measurement

The decomposition and formation of water molecules determine the protonation and deprotonation processes at the catalyst surface. Detecting interfacial water is particularly challenging because it is located between two condensed phases. Herein, we combine electrochemical in situ Raman and infrared spectroscopy with computational techniques to study the interfacial water on snowflake-like 1 T/2H-xMoS2/Cu2S (1 T/2H-MxCS). The snowflake-like Cu2S prevents the aggregation of modified MoS2 nanoflowers. The 1 T/2H-M0.02CS electrocatalyst exhibits excellence electrochemical performance, with a low overpotential of 59 mV and Tafel slope of 56 mV dec−1. This outstanding property can be ascribed to the interface and the formation of 1 T-MoS2, which not only decreases the activation energy required for the reduction reaction but also provides additional active sites for the catalytic reaction. Density functional theory calculations (DFT), in-situ Raman, and FT-IR spectroscopy were used to further elucidate the mechanism of electrocatalytic performance. This strategy offers new insights into enhancing the electrocatalytic activity of transition metal sulfides and a deep understanding of the HER mechanism.

Exploring the transformation: High-dosage gamma irradiation's role in tuning structural, optical, and electrical properties of cadmium-doped lead sulfide (PbS) nanoparticles

The effects of gamma irradiation on Cadmium-doped PbS (Cd-PbS) nanoparticles are thoroughly examined in this lattice study. The study sheds light on the changes in structural, morphological, and electrical properties brought about by Cd doping and gamma irradiation by employing a variety of methods such as X-ray diffraction, FESEM imaging, EDAX analysis, Raman spectroscopy, photoluminescence (PL) spectra, and Hall effect measurements. The Cd-doped PbS shows a fluctuating crystallite size as the average size first increases by ∼3 nm and then decreases by ∼3 nm with Cd concentration. This is due to the induced strain by the Cd dopant, which has a smaller ionic radius compared to Pb ions. With Cd substitution, the bandgap of PbS first decreases from 2.29 eV to 2.19 eV and then increases with mild fluctuations. Meanwhile, gamma irradiation causes these changes, decreasing the bandgap from 2.19 eV to 2.03 eV for lower Cd concentrations (x = 0.005) and increasing it to 2.41 eV for higher concentrations (x=0.01). The Hall data shows a wide range shift in electrical characteristics between the cadmium doped gamma-irradiated sample, and the pure sample, PS0. The electrical mobility increases from 6.05 V−1s−1 for PS0 to 4.95×102 V−1s−1 for GPS3 (higher cadmium concentration of x = 0.02), indicating a significant enhancement in which charge carriers can move through the material post-irradiation. Electrical resistivity shows a drastic increase from 4.42×101 Ωcm in PS0 to 9.41×102 Ωcm in GPS3, suggesting a marked increase in electrical conductivity post-irradiation. The findings demonstrate considerable changes in crystal characteristics, morphological transformations, increased crystallinity, and changed electrical properties, showing the promise of gamma-irradiated Cd-doped PbS in advanced optoelectronic device applications.

Iron-based graphene composite for oxygen reduction reaction in alkaline media: Electrocatalytic activity and lifetime evaluation

The development of electrocatalysts with high catalytic performance and low costs for oxygen reduction reaction (ORR) is still challenging. Herein, an overall solution for ORR in alkaline media, from the catalyst synthesis to catalyst regeneration and to the development of a rapid, reliable and easy approach for electrode surface evaluation, is presented. We focused on the development and characterization of an efficient material for ORR in alkaline media, α-Fe2O3 N-doped graphene (Fe-N-Gr). The associative pathway for the four electron transfer ORR mechanism is sustained by the Raman spectra recorded from the electrode surface. We highlighted the possibility of catalyst regeneration by a simple electrochemical method. After two regeneration rounds and 1500 cycles in O2-saturated 1 M NaOH, the catalyst still retains 40.8 % catalytic activity. Finally, as a part of the overall solution, we demonstrated that a methodology based on Raman spectroscopic measurements and machine learning algorithms can be applied for graphene-based catalysts lifetime investigation.

Copper tantalum nitride (CuTaN2) thin films prepared by reactive radio-frequency magnetron sputtering

RF reactive sputtering was used to deposit copper tantalum nitride (CuTaN2) films from a Cu/Ta target in an environment containing a mixture of argon and nitrogen at two different substrate temperatures: room temperature and 200 °C. The films were studied by SEM, EDS, XRD, Raman spectroscopy, spectrophotometry, and resistivity measurements. The deposition conditions significantly impacted the morphology of the films, which varied from smooth, void-free films at high nitrogen concentrations and at room temperature substrates to cauliflower-like grains with voids at low nitrogen contents and elevated substrate temperatures. Despite the target’s 1:1 Cu: Ta ratio, the stoichiometric analysis showed a lower Ta content in the deposited film. The films produced on silicon substrates were polycrystalline, whereas those deposited on glass substrates were amorphous. The band gap (0.9 eV to 1.55 eV) and film resistivity (20 kΩ-cm to 76 kΩ-cm) are strongly affected by the nitrogen fraction in the sputtering gas. Increasing the nitrogen percentage in semiconductor films results in smoother films with larger bandgaps (approximately 1.5 eV), higher resistivity, and compositions closest to those of stoichiometric CuTaN2.

Enhancing Carrier Mobility in Monolayer MoS2 Transistors with Process-Induced Strain.

Two-dimensional electronic materials are a promising candidate for beyond-silicon electronics due to their favorable size scaling of electronic performance. However, a major challenge is the heterogeneous integration of 2D materials with CMOS processes while maintaining their excellent properties. In particular, there is a knowledge gap in how thin film deposition and processes interact with 2D materials to alter their strain and doping, both of which have a drastic impact on device properties. In this study, we demonstrate how to utilize process-induced strain, a common technique extensively applied in the semiconductor industry, to enhance the carrier mobility in 2D material transistors. We systematically varied the tensile strain in monolayer MoS2 transistors by iteratively depositing thin layers of high-stress MgOx stressor. At each thickness, we combined Raman spectroscopy and transport measurements to unravel and correlate the changes in strain and doping within each transistor with their performance. The transistors displayed uniform strain distributions across their channels for tensile strains of up to 0.48 ± 0.05%, at 150 nm of stressor thickness. At higher thicknesses, mechanical instability occurred, leading to nonuniform strains. The transport characteristics systematically varied with strain, with enhancement in electron mobility at a rate of 130 ± 40% per % strain and enhancement of the channel saturation current density of 52 ± 20%. This work showcases how established CMOS technologies can be leveraged to tailor the transport in 2D transistors, accelerating the integration of 2D electronics into a future computing infrastructure.

Effect of Dual-Organic Cations on the Structure and Properties of 2D Hybrid Perovskites as Scintillators.

Two-dimensional (2D) hybrid organic-inorganic perovskite (HOIP) crystals show promise as scintillating materials for wide-energy radiation detection, outperforming their three-dimensional counterparts. In this study, we synthesized single crystals of (PEA2-xBZAx)PbBr4 (x ranging from 0.1 to 2), utilizing phenethylammonium (C6H5CH2CH2NH3+) and benzylammonium (C6H5CH2NH3+) cations. These materials exhibit favorable optical and scintillation properties, rendering them suitable for high light yield (LY) and fast-response scintillators. Our investigation, employing various techniques such as X-ray diffraction (XRD), photoluminescence (PL), time-resolved (TR) PL, Raman spectroscopy, radioluminescence (RL), thermoluminescence (TL), and scintillation measurements, unveiled lattice strain induced by dual-organic cations in powder X-ray diffraction. Density functional theory analysis demonstrated a maximal 0.13 eV increase in the band gap with the addition of BZA cation addition. Notably, the largest Stokes shift of 0.06 eV was observed in (BZA)2PbBr4. The dual-organic cation crystals displayed >80% fast component scintillation decay time, which is advantageous for the scintillating process. Furthermore, we observed a dual-organic cations-induced enhancement of electron-hole transfer efficiency by up to 60%, with a contribution of >70% to the fast component of scintillation decay. The crystal with the lowest BZA concentration, (PEA1.9BZA0.1)PbBr4, demonstrated the highest LYs of 14.9 ± 1.5 ph/keV at room temperature. Despite a 55-70% decrease in LY for BZA concentrations >5%, simultaneous reductions in scintillation decay time (12-32%) may work for time-of-flight positron emission tomography and photon-counting computed tomography. Our work underscores the crucial role of dual-organic cations in advancing our understanding of 2D-HOIP crystals for materials science and radiation detection applications.

Rapid CO2 laser treatment of Pt–Fe MOF for efficient electrochemical hydrogen evolution reaction

The quest for efficient hydrogen production via electrochemical water splitting has led to extensive research on catalytic materials. This work focuses on enhancing the catalytic functionality of metal-organic frameworks (MOFs) by incorporating platinum (Pt) to improve the performance of the hydrogen evolution reaction (HER). Fe-based MOFs mixed with platinum precursors were altered through laser treatment, which caused considerable changes in their structure and catalytic activity in just 3 min. This was achieved without the need for vacuum or an inert atmosphere. Characterization techniques including X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electrochemical measurements were used to characterize the synthesized materials. The laser-treated Pt–Fe MOF demonstrated outstanding HER performance with 3.5 wt% Pt content, outperforming commercial 20 wt% Pt/C catalysts, and exhibiting good stability even after prolonged cycling. These results highlight the potential of laser-treated MOFs for efficient and cost-effective electrochemical hydrogen generation.

Hydrothermal Destruction and Defluorination of Trifluoroacetic Acid (TFA).

Per- and polyfluoroalkyl substances (PFAS) have received increased attention due to their environmental prevalence and threat to public health. Trifluoroacetic acid (TFA) is an ultrashort-chain PFAS and the simplest perfluorocarboxylic acid (PFCA). While the US EPA does not currently regulate TFA, its chemical similarity to other PFCAs and its simple molecular structure make it a suitable model compound for studying the transformation of PFAS. We show that hydrothermal processing in compressed liquid water transforms TFA at relatively mild conditions (T = 150-250 °C, P < 30 MPa), initially yielding gaseous products, such as CHF3 and CO2, that naturally aspirate from the solution. Alkali amendment (e.g., NaOH) promotes the mineralization of CHF3, yielding dissolved fluoride, formate, and carbonate species as final products. Fluorine and carbon balances are closed using Raman spectroscopy and fluoride ion selective electrode measurements for experiments performed at alkaline conditions, where gas yields are negligible. Qualitative FTIR gas analysis allows for establishing the transformation pathways; however, the F-balance could not be quantitatively closed for experiments without NaOH amendment. The kinetics of TFA transformation under hydrothermal conditions are measured, showing little to no dependency on NaOH concentration, indicating that the thermal decarboxylation is a rate-limiting step. A proposed TFA transformation mechanism motivates additional work to generalize the hydrothermal reaction pathways to other PFCAs.

Silicon-tin thin-film anodes for low and high power-density lithium-ion batteries

Silicon (Si) is a promising replacement material for graphite, the commonly utilized anode material in lithium-ion batteries (LIBs). Si has a theoretical specific capacity up to 11 times higher than that of graphite. However, pure Si has two main issues: high electronic resistivity and significant volume change during charge/discharge cycling. To overcome these issues, Si was alloyed with high-conductivity materials. In this contribution, physical vapor deposition was utilized to produce binderless silicon-tin anodes for LIBs. Tin is a lithium-active alloying material that has high electrical conductivity and high specific capacity (i.e., up to three times that of graphite). Electronic resistivity, residual film stress, X-ray photoelectron spectroscopy, Raman spectroscopy, and cyclic voltammetry measurements were performed to thoroughly analyze the deposited Si-Sn films and help understand their charge/discharge cycling performance at low and high C-rates. At a low C-rate of 0.5 C, the alloyed films did not show any improvement compared to pure Si. However, the alloyed films showed better performance compared to pure Si when tested at a high C-rate of 10 C. Si-Sn films with (40 – 50 wt.% Sn) were able to retain a specific capacity of around 680 mAh g−1 after 1000 cycles.

Hybrid graphene-high-aspect ratio plasmonic nanograting systems

One-dimensional plasmonic nanogratings (1D-PNGs) with high aspect ratios and narrow grooves promise enhanced coupling for hybrid graphene systems with the localized surface plasmon of the metallic grating and graphene surface plasmons. However, both the fabrication of the 1D-PNG and the application of graphene to it are difficult. We developed 1D-PNGs with a high aspect ratio of 15 and narrow grooves of 100 nm in width using the tapered mold method and a dry graphene-transfer procedure. Raman spectroscopy measurements showed that monolayer graphene was successfully transferred onto the 1D-PNGs, and the graphene was strongly doped with Au in the 1D-PNGs. Graphene on narrow grooves (free-standing graphene) demonstrated an almost identical p-doping level to graphene on Au because the narrow groove width allowed sufficient doping by Au for graphene on grooves. Reflectance measurements showed that the 1D-PNGs exhibited polarization- and wavelength-selective absorption at infrared (IR) wavelengths, and the effect of graphene blue-shifted the absorption peak wavelength induced by the surface plasmon resonance of 1D-PNGs. Numerical calculations agree well with these experimental results and indicate that the electric field strongly localizes on graphene in the grooves. Moreover, the doping level tunes the absorption wavelength owing to the coupling with graphene plasmons and the surface plasmon resonance of 1D-PNGs. This could provide electrical tunability to the graphene plasmons. Our fabrication procedure produced hybrid graphene-1D-PNGs with high aspect ratios and narrow groove systems for IR wavelengths. This system can contribute to developing high-performance electrically tunable graphene-based IR photodetectors, tunable IR emitters/absorbers, and biological sensors.